1. Field
This disclosure relates generally to semiconductor devices, and more specifically, to semiconductor device with lead frames.
2. Related Art
Some types of packaged semiconductor devices include an integrated circuit die mounted on a lead frame. Lead frames are commonly manufactured by stamping/punching preformed sheets of metal such as copper, copper alloys, and iron-nickel alloys into desired shapes. Lead frames may also be made by plating metal in a desired pattern onto a carrier that is subsequently removed, with use of a variant of this technique called LIGA, (German acronym for Lithographie, Galvanoformung, Abformung—Lithography, Electroplating, and Molding), and other specialized techniques.
The lead frame includes conductive leads that extend from close proximity to the die to beyond the outer edges of the package body. Wire bonds are formed between the die and the lead frame to form a die assembly that connects the die to bond pads on the lead frame. The die assembly is then placed in a mold that encases the die and the wire bonds or other electrical attachments. Mold compound is inserted or injected into the mold. Mold encapsulant is formed around the die and the wire bonds to protect the die and wire bonds from corrosion, water, and external forces that may damage the die or break the wire bonds.
Environmental mandates are causing a shift away from the use of lead solder in electronic components. Use of lead-free solder has caused solder reflow temperatures to increase to approximately 260 degrees Celsius. This higher reflow temperature makes it more difficult for the mold compound to remain on the lead frame and can cause the mold compound to delaminate from the lead frame during testing and/or operational conditions. Since the semiconductor devices may be used in a variety of environmental conditions, it is desirable for the molding compound to adhere to the lead frame and other components in the package to avoid corrosion of the components due to environmental moisture and/or chemicals.